Distributor for use in telegraphy or the like



March 14, 1933. E K, SANDEMAN 1,900,954

DISTRIBUTOR FOR USE IN TELEGRAPH! on ms LIKE Filed Feb; 10, 1931 :s sheets-sheet 1 INVENTOR EDWARD K. SANDEMAN ATTORNEY March 14, 1933.

E. K. SANDEMAN 1,900,954

DISTRIBUTOR FOR USE IN TELEGRAPHY OR THE LIKE Filed Feb. 10, 1931 1 1 1 r r 1- 1 e r 1 e 1 1 r fie 9 1'21 r 1 IZI- r5 6 F m E] m 22 m 21 INVENTOR EDWARD K. SANDEMAN ATTORNEY 3 Sheets-Sheet 2 March 14, 1933. SANDEMAN 1,900,954

DISTRIBUTOR FOR USE IN TELEGRAPH! OR THE LIKE File Feb. 10, 1931 3 Sheets-Sheet 5 L Jl 9 5? 2 9. 2 ga 92 4 52 1 :91

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FIT]

IN V E N T 0 R EDWARD K. SANDEMAN ATTORNEY l atentecl Mar. 14, 1 93?;

EDWARD KENNETH SANDEMAN, OF ALIDWYCH, LONIDON; 'ENG ILiNID, A SSI INTERNATIONAL STANDARD ELECTRIC CORPORATIQN, or Nnw zonx, N;. Y.

DISTRIBUTOR FOR USE IN TELEGRAPHY OR THE LIKE Application filed. February 10, 1931, SerialNo. 514,761, and iniGreat Brltain'February 12, 1930;

This invention relates to means for distributing the use of a communication channel, in turn to a number of telegraph transmitters and receivers.

The object of the invention is to provide a means or method for enabling a large number of telegraph instruments to operate over a connecting channel, and which does not necessarily require the employment of high speed mechanical moving parts.

According to one feature the invention comprises a plurality of energy translating devices, for instance vacuum tubes. arranged in groups. The number of translating devices in any intermediate group lies intermediate the number of such devices in the adjacent groups and means are provided for disabling or blocking the translating devices in such a way that at any particular instant only a predetermined number of translating devices in each group is permitted to be operative as energy translators and the selection of such operative translators is obtained automatically by electrical or mechanical effects impressed upon said translating devices.

The following description has reference particularly to an embodiment employing several valves arranged in a pyramid form so that a multiplicity of signal or code indications influencing their input circuits may be distributed. in time to a common circuit; or at the receiving end a plurality of code indications may be sorted out by asimilar arrangement. to operate the required and corresponding receiving instrument or printer.

Other features of the invention'will be apparent from the following description in which 2' Fig.1 illustrates schematically a distributor arranged and operating according to the principles of the present invention.

Fig. 2 is a curve illustrating the manner in which the grid bias on the tubes of Fig. 1 may he modified to give intermittent blocking of the valves.

Fig. 3 illustrates schematically a modified embodiment of a distributor according to the present invention. 1

Fig. 1} illustrates schematically a stillfurand ther modification of the" present invention,

Fig. 5 is-a diagram use'd to illustrate a condition of the valves which may occurin the arrangement of Fig. 3. v

In Fig. 1 is shown a schematic arrange ment for a transmitter terminal in accordance with this invention. The part'above the chain dotted line consists of eightgraphi cal portrayals of biasingor paralyzing voltage waves a-pplied to the grids of certain valvesin the lowerpart of the figure. The

lower part of the figure contains a valve pyramid fulfilling the function of a distributor, that is connecting a number of sending devices inturn to the same circuit. I

A, B, C, D and E are respectively groups of two, four,eight and sixteen and one thermionic valve numbered serially ineach row. I

The-valves are coupled together so as toform an amplifier with onefoutp ut and sixteen'inputs, corresponding to the sixteen grid cir cuits of valves D tov D Valve E may conveniently be a detector valve, and the other valves are ordinary amplifiers when in an operating condition. Valves D and D have their output coupled in parallelto the input of valve C valves D and D... have their outputs in parallel coupled to the inputof C Valves C and C havetheir outputs in parallel coupled to the input B the pyramid is built up in a similar manner. a is a paralyzing square wave of frequency a equal to. the number of letterspersecond per instrument 4 nl lm F 60 ,B y and 8 are square waves of frequency respectively 2a, 4a, and 8a used for paralyzing purposes as describedbelow, 1 a2, [32, 2, and 82 are squarewaves of frequency respectively equal to al, 31,71 and81, but in opposite phase also used for paralyzing purposes;

The paralyzing wave a1 is applied: to the grids of valves D D D ,.D D D D D and the paralyzing Wave a2 is applied to the grids of the'valves D D D D D D D D To the grids of'G G G and The whole of C are applied a vparalyzing ave,81 Qwhilst lOO to the other valves of the group C a paralyzing wave ,82 is applied. Similarly waves land 2 are applied to alternate valves in group B whilst valve A has applied to it a paralyzing wave 81 and valve A as a paralyzing wave 82. It will be seenthat the valves near the apex of the pyramid are applied with paralyzing waves of high frequency and those near the base of the pyramid with paralyzing waves of low frequencies. The paralyzing wave 81 is applied to the grid of valve A in such a way that during'positive half cycles of'81 valve A 1s in an operatlng condition and durlng negatlve half cycles of 81 valve A is in a nonoperating condition. Fig. 2 shows the way in whichbiasing potentials are applied to A The aXisIZ) is plate current and Vgisgrid'voltage. En is the biasing potential required for optimum performance of the valve as an amplifier. E10, is the biasing potential requiredto make the valve completely inoperative for signals of the new magnitude 7. 7 i is the value of steady bias applied to the applied to'the grid at any time. Ea=g4E +Em I valve. Y=-}(Ep-En) 'is the amplitude of the paralyzing wave. Since the paralyzing wavesa're allsquare waves it follows that any valve to which a paralyzing wave is applied in the above manner is rendered completely inoperative'iand completelyoperative during 7 alternate'equal and contiguous time intervals.

The lines onFig. 1 running from the axis of each wave (041, B1 etc. 02, ,82 etc.) are intended to indicate the point on the valve pyramid at which this wave is applied. 7 The circuit by which it is applied will be described later. For clearness in description the axis sets up one new letter T of time along which the waves are shown has been divided into sixteen time intervals each equal in duration to half a period of the waves 81 and 82. During a time equal to the sum of these sixteen time intervals one complete cycle of eventsoecurs: each transmitter sent overthe line L. Y r I Consider theinterval numbered ('1'). During this interval wave 81 is positive and 82 is negative so] that valve A 1s operative and valve A 1s inoperat ve, so that all currents coming from'relay ton'gues 2, 10, 6, 14, l, 12, 8, 16 are'block'ed.

Also wave 71 is positive. and wave y2 is negative so that valve B is operative and valve B 1s inoperativefthus nullifying any currents orlglnating 1n relay tongues3, 11,

'Similarly-valve C1 is Operative and C inoperative so that currentsfrom relay tongues 5 andi13 are blocked. I f Finallytheparalyzmg of valve D fby a2 blocks currentifroin relay tongue 9, leaving only .a path for currents originating from generator C Wei relay tongue'l if operated by from each transmitter relay 1. This path proceeds by valves 1 3 C carried out it will be referred to as scanning and the relay which at any'moment is effectively connected to the line will be referred to asthe scanning point.

Returning to Fig. 1, P P and P are three printing telegraph transmitters of known type which operate by setting updilferent cornbinations'of the relays R R R R R R etc. Each of the relays has two positions corresponding to a marking position and a spacing position. In the marking position the tongue (T T etc.) is held down on the corresponding contact to the common bus bar KKwh'ich is energized by AC a source high frequency current which may be re ferred to as'the carrier frequency. The freque-ncy of this source is not critical provided itlies well above the frequency range which the telegraph is required to fill. F or example, if 1t were required tooccupy a range'of 00' *l 't bl l th' 'f" 0 eye es sui a e va ues ror e carller iequency would be 1,000 cycles to 10,000 cycles a".

and it would befpc'ssible to exceed this limit in either direct-ion'provided the amplifiers following are capable of handlingthesideband products of modulation formed by the switching on'and oif'of the carrier frequency by the'relay tongues-T T etc.

- By means of a rotating device, indicated symbolically by W in Fig. 1, the three printing telegraph transmittersP P and P are caused to operate in turn, each setting up a letter on its five associated 'R relays during time T9 and leaving set up during time T after. which the process is repeated with q the next. letter. In general the value of Ts will be much smaller than the value ofT Thoughnot essential to the'method, the commencements of each of-the threeintervals T81, T82, T83, corresponding respectively to theprinters'P P and P most convenient-- ly may be separated from one another by equal time intervalsif the time taken to set up any' relays S is omitted. (These relays S represent sparerelays, occurring because the valve pyramid requires a number of relays equal to a power of two, while the printing telegraphs require a number of relays equal to a niultiple of five). The same is true of-the'com nencements of each ofthe' inter vals Ti T and T which mark the termi nations of intervals T81, T82 and T83. It is are convenient to associate the cycle of events with a rotating vector Vt which may be identified with a particular line along a radius of the rotating device (i. e. the device actuating the printer), the angular position of which determines which transmitter is ac-. tuated, i. e. caused to move its transmitting tape one letter forward and sobreak down one combination of its five relays and set up the next combination. The position ofthe scanningpoint may conveniently be associated with a. rotating vector Vs. It is evident that the vectors Vt and Vs must on the average ro-' tate at the same rate, small fluctuations in rate being permissible provided the Vt never passesVs or vice versa; this last proviso is obviously necessarysince scanning of a relay and change of relay setting must evidently not take place at the same time. This will be considered in detail later. Each vector makes one revolution in time all be derived from one or'more' sets of current generated by an alternator on the axis of W, the relative positions of Vtzand Vs can evidently be maintained with extreme precision at the transmitting end.

A practical difliculty occurs in generating waveswhich are exactly square in form and it isprobable in practice that the beginnings and the ends of the time intervals during which a valve is intended to'be maintained at constant voltage, the valve grid biasing voltage will tend to move towards the value corresponding to the axis of zero voltage of the wave. In other words, a rounding off of the corners of the waves will occur. In the 7 case of the wave of highest frequency, this will probably not be serious because it will simply mean that the transmittedsignal will approximate to the form in which it is re- I; ceived, (i. e, the effect will be similar to suppression of the high frequency components of the square wave). In the case of the waves which are not the waves of highest frequency, as long as the period of rounding is considerably smaller than half the full period of the waves of highest frequency the rounding will probably not be serious,'but as soon as this roundingapproximatesin duration to half the period of thewave of highest frequency it means that the operation of the valves to which this wave is applied will be indeterminate during the period of the rounding. That is, during the period over which the rounding takes place the valve will not be fullyoperated or fully paralyzed as the case may be. It is therefore desirable to devise some system which will operate sat.- isfactorily with waves which are not square waves. The most convenient-type oiiwave to use is evidently a sine wave since thisris most easily generated, though the scope of above, that the'rounding of the so-called nat carried square waves is negligible for waves 71 and 2v and 81. and 82, and these waves are therefore kept unaltered and the part of the valve pyramid to which they are applied remains unaltered, as does also their manner ofapplioation. The following replacements fof waves a1 and a2 and ,81 and ,82 hashowever been made.

Wave a2 is replaced by waves a and'ad Wave ,81 is replaced by waves ,Gd and ,8?)

Wave ,82 is replaced by waves B0 and ,86Z

For simplicity in explanation the waves (11 and a2 and ,81 and ,82 are shown dotted along the same axes as the waves ad, orb, 4x0, and ad and [3a, 8b, ,80, ,801.

Ba is a sine wave of the same frequency as ,81 and of such phase with regard to it that it reaches its maximum in either direction /3 of a period after the square wave Bl has changed polarity.

- [3b lags on wave ,Ba

wave B1 changes polarity.

Referring to Fig. 2' it wasseen that amplitude Y of the square wave is-given by T} (Ep-En) Ep is thevoltagerequiredto dition. It is evident that providing the amplitude of the signals transmittedis made so that it'r'eaeh es a maximum at a point A; of 'a period before Wave a1 is replaced by waves ad and a?) i considerablyless thanEn, as can easily be done, En is not-critical in value. This mleans that the value of- (E gar-En) Y: is not a critical figure. It follows that if it be'inv sured that the peak amplitude of wave Ba always lies above the'value required to paralyze the value a suitable choice of conditions-can easily be made suchthat the valve will operate satisfactorily for any value'of the par alyzing wave lying between 1say +Mg and +N; Similarly, since any value'or negative I voltage greaterthan a certain amount'will secure paralysis of the valve,{it follows that conditions can be arranged such that complete paralysis occurseifectively with'the value of negative voltagebf N and, of

course, the valve remains fparalyzed when this voltage varies anywhere between "N I and -M.

It follows therefore that, any valve having the wave ,Ba applied to it is definitely operative in intervals 1, 2, 9 and 10 and is completely paralyzed in intervals'5, 6, 13 and 14. During eriod's's, 4, 7, 8,11, 12, 14. and

16 the condition of the valve can best be 7 regarded asindeterminate; From the above explanation it is immediately obvious what is'the-condition-of any valve in any interval when supplied with agiven .wave;v

It-will be noticed that valves A and A have-waves of completely opposite phase. This is also'true for valves B and B and also :for'valves B and B and for valves C and C and so on. It follows thereforethat -whe'n any valve of one of such a pair isope apex, no other path can be open. e. g. "Figure .5. :is shown the condition ofEafiairs erative the-other valve of the pair is inop-' erative. It follows at once that if a path is open vfrom any oneof theD valves to the In 'ininterval 1. .The solid circle representsa valve completely blocked, the half solid circle represents in an intermediate condition j and the other circle'r-epresents a valve entireber of valves has been done in row 13. The

ly operative. vThe-order ofopening of the paths. isidentical with that occurringin the arrangem'ent of Figure 1 and an identical system of'cross'connection between relaysrand valves must be employed.

Figure 4 employs a systemof waves identi+ .cal with that shown in Fig. 3 and applies them to a di'fiierent arrangement of valves. The manne-r in=which the waves-are applied is however "analogous; In the pyramid of valves, valve A1 in said figure has been 'replaced by two valves A andA -valve A in saidfigure has been replaced by twovalves A and A A similar doubling of the numremaining valves remain the same. Consideringthecombinations, 01": valves A and A it is evident that A is'operative during time intervals 1, 2, 3and land A is operative during time intervals '5, 6, 7 and 8. It follows therefore that a path is available through 1 I the combination A and A during thetime -intervals '1 8 that is,-during exactly the same intervals :as the path :was available when the square wave was-applied. f Similar comments mayzbera-ppliedtoi ev'ery' group. I-Itis there'- fore evidentthatrpaths will be.availablein the manner identical in every way with the manner in whichpaths become available in the former,arrangement. .An analysis. of each' time inter-val along thelines ofFigure ,apex of the valve and which'containno valve 5 shows' alsothat a number of indeterminate paths-exist. That is to say, pathswhich: are tracedsfrom the base of the pyramid to the completely paralyzed but. oneor more valves V as. indeterminate.

Q can be changed: by adjusting the amplitudes whosecon'dition has previously been regarded This condition of aifairs of the paralyzing waves. For instance, it would probably belpossibleto secure-satis factory operation by adjusting the paralyzing wave -so that during the indeterminate period foraaparticularrvalvetheamplifioa tion of :the valve :is always appreciably "less than 'duringithe period at which it is supposed'toibe operating. An alternativemeth- 0d, of course, would be the-supplying of two paralyzing Waves of .the'same magnitude to-thesame valve, differing in frequency.

Whatiscclaimedlis: '1. An arrangement for .use'ina, telegraph system employing a distributor comprising several valves .adapted;to operate as a multi- Iple'switching arrangement, a means for'providmg a. substant1-ally square Wave, said means comprising .an amplifier valve, and a voltage operated device comprising a neon lamp shuntedby a condenser. associated with theoutputtcircuitsof said amplifier valve.

'2. .A distributor foritelegraph or the like comprising-valves arranged'in a plurality of groups,-circuits:adapted :to join and interconnectrthe-numbersof ,valves of the groups in a convergent series, and meansadapted to vfeed paralyzingwaves. to said valves to render them periodically operative, inoperative, or

in-anintermediate state so that at any particularmoment only ;a predetermined number (usually one) of conductive paths through 'thevalves in the largest .group to 1 the valves inthe-smal'lestgroup ,arefestablished.

' '3. A distributor according to claim "2 wherein all thevalves of at'lea'st one groupare arranged in pairs there being means 4. .An; arrangement for use in a; telegraph system or the l ke comprising groups of valves, circuits, adapted: to 30in and interconmet the numbers of-valvesot the groups in a convergent series, and means ;-.adapted to 'feediparalyzing-waves to the valves in .di-fierent groups, :a valvelof the group with-the largest 'number of valves having paralyzing wavesoftheelowest frequency. and the valves ofithe other groups having paralyzing waves Whose: frequencies are graded-accordingly.

.5.}A distributor for telegraph or the-like comprising groups-of valves, circuits adapted to join and interconnect the numbers -of valves .of the groupsin :a convergent series,

means, for applying qdiifere'nt paralyzing waves to' the valves in different groups wherein paralyzi-ngpotentials on at least one of the-groups of valves are in-the form of a plurality-of vvavesi adapted to simulate the eflectofa single square wave.

= 6. A distributor vfor: telegraph or the like comprising valves arrangedi-n a,.p=l-ural ity of ggrou-ps, circuits adapted to join and interconnect the numbers of valves of the groupsin a convergent series, and means for applying paralyzing waves to the valves in different groups wherein paralyzing potentials on at least one of the groups of valves are in the form of a plurality of waves displaced in phase so as to simulate the effect of a single square wave. r

7. A distributor for telegraph or the like comprising valves arranged in a plurality of groups, circuits adapted to join and interconnect the numbers of valves of the groups in a convergent series, and means for applying paralyzing waves to the valves in different groups wherein valves to which are ap-v plied paralyzing waves of other than square my name this twenty sixth day of January EDWARD K.- SANDEMAN.

form are arranged in pairs or multiples correspondlng to the number of waves replaclng the square waves, each pair or multiple have-t ing common input and commonoutput circuits.

In witness whereof I hereunto subscrlbe 

